It's not my fault!!! It's student-of-Alan-Borning's fault! :-)

Your point is well taken.  I usually don't use pools.  However, I was 
just doing as quick a port as I could, and so didn't change the use
of pools.  I'll go make the changes right now.

Thanks,
Schwa



On Wed, May 16, 2001 at 08:53:58AM -0400, Jarvis, Robert P. (Contingent) wrote:
> Take a look at
> 
> 	http://www.smalltalksystems.com/publications/pools.doc
> 
> This is Juanita Ewing's paper on pools.  At the very end she says
> 
> 	Because pools are data, avoid pools whenever possible.
> 	Instead, create a class that encapsulates the data in
> 	the pool and replace existing pool variable references
> 	with messages.  Your code reuse and ability to store
> 	your application in source form will improve.
> 
> HTH
> 
> Bob Jarvis
> Compuware @ Timken
> 
> > -----Original Message-----
> > From: Joshua Channing Gargus [mailto:schwa at cc.gatech.edu]
> > Sent: Wednesday, May 16, 2001 8:46 AM
> > To: Squeak Mailing List
> > Subject: FileOut/FileIn problem
> > 
> > 
> > Hi,
> > 
> > I'm running into a problem that I'm sure some long-time Smalltalker
> > will be able to easily help me with.
> > 
> > I've done a port of Cassowary 
> > (http://www.cs.washington.edu/research/constraints/cassowary/)
> > to Squeak, and all is well in the image that I ported it in.  However,
> > when I try to file it out and file it in to a clean image, problems 
> > arise.  The problem has to do with pool variables; when I run the 
> > demos, I get a walkback resulting from a nil value from a value in
> > the pool.  However, if I inspect the variable in the debugger 
> > (highlight it with the cursor, and Alt-i), it is what it should be.
> > 
> > I think that this problem results from me transcribing the Cassowary
> > classes in alphabetical order instead of the order necessary to 
> > ensure proper pool initialization.
> > 
> > I can fix this problem by recompiling two classes as follows:
> > ClSimplexSolver compileAll. ClSymbolicWeight compileAll
> > I guess I could put this in the postscript, but I'd rather learn
> > what the problem is and fix it rather than work around it.
> > 
> > I'm attaching my changesets.  Experience this bug by:
> > 
> > 1. File in Cassowary.1.cs
> > 2. File in Cassowary-Demo.1.cs
> > 3. Evaluate 'ClCrossedQuadDemo new openInWorld'
> > 
> > nil gets sent the message negated.  This is because Squeak thinks that
> > ClEpsilon (actually 'ClConstants at: #ClEpsilon') is nil.  However,
> > inspecting the value of ClEpsilon shows that it is 1.0e-8, as 
> > it should
> > be.
> > 
> > I hope someone can help me, as I'd really like to make this cool 
> > constraint framework available!
> > 
> > Thanks,
> > Schwa
> >